Beam Instrumentation in the HL-LHC

Insertion RegionsRhodri Jones

HL-LHC PLC - 18th Jan 2013

Current Equipment

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• Existing LHC Experimental Insertions– BPMs

• Directional couplers in common beampipe regions (Q1, Q2, Q3)– Stripline Length 120mm– BPM length 256.4mm (cold - welded) – 285mm (warm - flanged)– Inter-electrode Diameter 61mm, 81mm (131mm also designed for Pt6)

• Button pick-ups in separated beampipe regions (Q1, D2, Q4-Q7 + Trigger BPM for Expt)– BPM length 203mm (cold - welded) – 285mm (warm - flanged)– Diameter 49mm, 61mm, 80mm (injection)

• Integrated BPMs in new TCT collimators– BLMs

• External to cryostat ~50 per side covering TAS to Q7– Luminosity monitors

• Ionisation chambers inside TAN in 1 & 5• CdTe detectors behind Y chamber in 2 & 8

– BTVs in injection regions

Current Equipment

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• Existing Equipment in Points 3,6 & 7– BPMs

• Striplines for large aperture in dump region (signal level)– including interlock BPMs

• Button pick-ups– cold in all SSS & warm near collimators & warm quads

• Integrated button pick-ups foreseen in new collimators– BLMs– BTVs

• Existing equipment in Point 4– Standard BPMs & BLMs– BCTs (2 DCCT & 2 Fast BCT per beam)– BSRT + undulator– BGI– Wirescanners– Special pick-ups

• Tune, Schottky, Head-Tail– BTV - Injection Matching

Foreseen HL-LHC Equipment

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• HL-LHC Experimental Insertions - BPMs– Propose to maintain directional couplers in common beampipe regions

• Position should be optimised to counter influence of 1 beam on other– Locate in between long range collisions– If not possible:

» Can gate on pacman bunches• More complex to set-up & less operationally robust (needs precise timing)

» Possibility to use alternative electronics• Diode orbit system will be tested after LS1• Sensitivity to separation to be determined (still needs some separation)

• Length of 220mm can be considered minimum for cold stripline BPM• Length of 285mm can be considered minimum for warm stripline BPM• The more we have the more robust the correction & feedback in this region

– Button pick-ups for separated beampipe regions if aperture <= 80mm– Do we maintain button in front of Q1?– Originally installed to measure zero crossing angle for TOTEM & ALFA– Do not forget trigger BPM for experiments

– If proved to be useful maintain integrated BPMs in all collimators

Foreseen HL-LHC Equipment

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• HL-LHC Experimental Insertions - BPMs

Current BPM locations

Proposed BPM locations

Could think of Duplicating in these regions for more

redundancy

Foreseen HL-LHC Equipment

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• HL-LHC Experimental Insertions – BPMs– Existing BPMSW

Foreseen HL-LHC Equipment

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• HL-LHC Experimental Insertions - Others– BLMs

• Maintain BLMs external to cryostat• Add cryogenic BLMs in all new Quadrupoles (6 per magnet)

– Proposed to distinguish between collision debris & beam loss– Integration to be foreseen at an early stage– Would welcome opportunity to qualify mechanical & electrical properties in

prototypes as they are tested

– Luminosity monitors• Do we maintain the need for monitors separate from experiments?

– Useful if we cannot rely on data from experiment under all conditions• Do we maintain the need for 40MHz operation?

– Considerably complicated current design

– BTVs in injection regions• Maintain current number in the layout

Foreseen HL-LHC Equipment

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• New Instrumentation for HL-LHC Experimental Insertions– Long Range Beam-Beam Compensators

• Optimal location will depend on optics (maintain 5m in Y chamber?)– Ideally require equal beta for H&V– Ideally require wire location at mean separation of long range collisions

• Propose to maintain current idea of in-collimator design– Needs staggered B1 & B2 space reservation before D2– Total of 2m per beam per side of each IR – combined with collimator?

– Crab Cavity Diagnostics• Current proposal is for Head-Tail monitors

– Either based on existing long striplines or higher bandwidth optical BPM currently being studied– Need to reserve 800mm space at suitable optics location

» 90 degree phase advance to give maximum crab effect– Do we want 2 measurement points?

» One as close as possible to IR?» One after crab cavities towards arcs to check compensation?

Foreseen HL-LHC Equipment

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• New Instrumentation for HL-LHC Experimental Insertions

Investigate foreseen collisions optics at these locations to see if they are compatible with an effective long range beam-beam compensator

ACTION: ABP

Foreseen HL-LHC Equipment

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• Instrumentation for HL-LHC Point 4– Maintain currently installed hardware– Upgrades to be foreseen for some instruments

• BSRT will already be partially redesigned during LS1• BGI design to be adapted for higher beam intensity• BCTs may also need to be modified• New fast wire scanners to be installed during LS2

– Influence of optics• Optics at emittance measurement devices

– Needs to be maximised in measurement plane if possible– Needs to be stable (or accurately measureable)

• Some BPM locations may need to be modified to match optics– Tune measurement BPLX currently placed at equal H & V beta location

Foreseen HL-LHC Equipment

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• New Instrumentation for HL-LHC Point 4– Beam Gas Vertex Imager (BGV)

• In development as possible alternative emittance monitor– Based on LHC velo concept– Gas injection required– Study underway to look at feasibility (HL-LHC funded fellow)– Requires total space of ~7m per monitor (possibly between Q6 & Q7)– Beta functions should be equal and as high as possible

– Additional Synchrotron Light Beam Line?• Currently already have 4 diagnostics on one line

– Abort gap, longitudinal density monitor, fast & slow cameras• Additional items that could be added for HL-LHC

– Halo diagnostics– Streak camera for study of crabbing

• Proposal to study feasibility of second optical line– New undulator near D4 on incoming beam

» Light extraction between D4 and D3– Re-investigate option of coupling out light from D2

Foreseen HL-LHC Equipment

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• New Instrumentation for HL-LHC Point 4– Beam Gas Vertex Imager (BGV)